Tenter clip



Sept. 19, 1961 M. M. ZUCK ETAL TENTER CLIP Filed March 28, 1960INVENTORS MATTHEW M. ZUCK flQHN E. WATERMAN FIG. 3

ATTO R N EYS United States Patent Matthew M. Zuclr, Warwick, and John E.Waterman,

'Chepatchet, RJ., assignors to Winsor & Jerauld Manufacturing Company, acorporation of Maine Filed Mar. 28, 1960, Ser. No. 17,984

- 3 Claims. (Cl. 2662) This invention relates to a clip and moreparticularly to an improved tenter clip that is particularly adaptablefor the lateral stretching of plastic webs by automatic machines.

Tenter clips have long been known and used in the art inconnection withtentering machines which stretch web material as it is fed to themachine. Many shapes of tenter clips have been designed for variouspurposes and theitem that perhaps has received the most widespreadtreatment has been the jaw of the tenter clip. The jaws have been shapedin various forms .primarily to. enhance the gripping relation thereofwith the web material. The various forms have included knife edges,-corrugated surfaces and other roughened surfaces; With the recentadvances that have taken place in the organic plastic web field, it hasbeen found thatthe plastic material will be greatly improved by thephysical act of stretching the material. Accordingly, tentering. ma-'chines, which were heretofore used primarily in connection withtextiles, have been found especially adaptable for use with organicplastic materials provided certain changes weremade inthe operation ofthe. machine. The major modification that must be made is the use of anentirely different tenter clip jaw. It will be apparent that when onetries to grip a plastic material, that in the first place the materialis not as thick as textile material would be and secondly it isextremely smooth, thus giving a very low coeflicient of friction.Consequently these physical factors give rise to difiiculties with theoperation of the tenter clip jaw. It is of course desirable-thatthe'plastic material be left intact while it is passed through thetentering machine and therefore the tenter clip jaw should not punctureor otherwise mar the material.

It is therefore an object of the present invention to provide a tenterclip which will have a jaw that will hold the plastic film or webmaterial against slippage.

Another object of the invention is an improved tenter clip with arocking jaw which will insure a large gripping area.

A still further object of the invention is to provide a tenter clip witha large gripping area over which the plastic web material is gripped athundreds of spaced locations With these and other objects in view, theinvention consists of certain novel features of construction as will bemore fully described and particularly pointed out in the appendedclaims.

In the accompanying drawings:

FIGURE 1 is a side elevational view of a tenter clip embodying ourinvention;

FIGURE 2 is an exploded perspective view of a portion of the jaw;

FIGURE 3 is a fragmentary enlarged view looking at the work engagingportion of the jaw; and

FIGURE 4 is a perspective view of the jaw assembly.

The tenter clip illustrated in the drawings is a link of a tentermachine chain having a base 11 which is adapted to ride upon the usualrails of the tentering machinery. The upper surface of the base 11 formsthe lower jaw member of the tenter clip which jaw member actuallyconsists of a hardened facing plate 12 affixed to the base member 11.Rising from the base member 11 is an with concavities 23 and 24 whichare sufliciently'deep.

3,000,073 Patented Sept- 2 arched portion 13 which overhangs the lowerjaw: portion of the clip. Mounted for swinging movement in the archportion 13 is an upper jaw member generally desig-' nated 14. The upperjaw 14 has an arm 15 extending; therefrom in a general verticaldirection when mounted within the clip and is adapted to engage cams(not shown) located at each end of the tenter machine. Upon suchengagement the jaw 14 will pivot in a" counter clockwise direction asseen in FIGURE 1 and will raise above the lower jaw 12 to allow webmaterial to he moved from the clipor to be guided between the jaws ofthe clip as the case may be. f

The surface engaging portion of the upper jaw 14 isformed by bifurcatingthe lower portion of the jaw into; two plate portions 16 and 17 (FIG.1). One or more feeler fingers 18 are mounted upon the plate portion 17and extend into slots 19 which are formed in the lower jaw 12 for apurpose to be presently described Between the plate portions 16, 17 thesurface engaging portionof' the upper jaw is mounted. This surfaceengaging portion is shown more particularly in FIGURE 2 and coir-i sistsof two bars 20 and 21 between which there isheld the work engagingmember 22. Thework engaging member 22 is preferably cylindrical and toaccommodatethis cylindrical shape, the bars-20 and 21 are formed- I tograsp the cylinder below the median thereof. Bars alignment of the workengaging member 22 with the:

lower jaw 12 is always insured. This comes about. because of thepivoting action of the work engaging. member 22 relative to the upperjaw, this pivoting tak? ing place about'the' pin 26. According to thepresentj invent the Work pping surface of the j'a'w'1'4' "a related tothe axis of the pivot of jaw 14 a distance greater than the distancebetween the axis of rotation of jaw 14 and the lower jaw 12. Thus in theclosed relation of the jaw 14, the work engaging edge of the workengaging member 22 will engage the lower jaw 12 and limit the clockwiseswing of the upper jaw 14. Tension on the material held between the jawsof the tenter clip will therefore only tend to move the upper jaw intotighter engagement with the material positioned on the lower jaw 12.

The surface of the work engaging member 22 has been found to be ofcritical nature. In order to hold the plastic web material, it isnecessary to provide a multiplicity of spaced minute projections whichwill engage the work at a multiplicity of spaced points along the lineof contact of the upper jaw with the web material. Preferably thesurface of the work engaging member 22 is a file cut surface andparticularly it has been found that a number 4 file cut renders optimumresults. It has further been found that by providing this surface on themember 22, that plastic web material will be held against slippageduring the travel thereof through the tentering machinery.

In operation, clips manufactured in accordance with the invention aremounted to form a continuous chain along the rails of the tenteringmachine. As plastic web material enters the tentering machine, the webis caused to pass between the upper and lower jaw members of the tenterclip. This is accomplished by maintaining he pivoting upper jaw memberin an open position by the use of cams (not shown) which engage theextending arm 15 of the upper jaw member. As the web enters the spacebetween the upper and lower jaw memhere, the pivoting upper jaw memberis released and engages the web by 'force of gravity; The first portionto engage, the web will-be the feeler finger 18 which will hold theupper jaw in open position until the edge of the web has been pulledoutwardly a sufficient distance so hat, the: edge will 'pass from underthe feeler finger 18 and then the upper jaw will make initialengagement, worl; engaging cylindrical member 22 then making contactwith the web material. As the web exerts a pulling force, the frictionalforce between the web and the contacting surface increases, thus causinga greater holdipgor gripping force thereon. Upon reaching the end of thepath of the tentering machine, the pivoting upper jaw member is releasedand the web leaves the area between the jaw members of the tenter clip.

The great holding power of the tenter clip made in accordance, with theinvention is occasioned by the provision of a multiplicity of minuteprojections, which in effect have quite sharp edges and which are bestobtained by using the No. 4 file cut above referred. Positive engagementalong a complete line is obtained by virtue of the pivoting action ofthe surface engaging portion of the upper jaw 14. A further advantage oithe instant invention may be readily ascertained since it will becomeapparent that when such a fine line of minute projections is provided,these sharp edges or projections will tend to wear after a period ofuse. Rather than having to change the entire upper jaw, whichis atedious operation and requires theknoeking u f h p o p n of h pp j o rplace t,v have provided avery siml'lll? construction where the Surfaceengaging memb r 2 may e ota d, a l gh am u t s v i s nte eb' nece saw olo en. h faste n scr 25 ha ho s... th wo pla e 20 an .1 o ethe nd rota ehe y d c m m 22 to. anothe nga Por o wher a e r y new ur ac l be pres edto h web h t l have th har c er s cs f a w jaw- Th no n y s uper o conact p ded t a o a e of ma n n s p oid c th he ins nt on u on 7 We claim:

1. A tenter clip for a tenter chain comprising a body having a plateportion for supporting a web, a clamp jaw pivotally connected to saidbody above said plate portion and having a free end depending towardsaid p e nd d p d t erec r o cla pi g wa b to said Pla e po on h aid freen of s d i w comprisi a P of damp bar sa d. bars b g ri n d generally pr to he pi ot n ax o s id ja a work' engaging member removably fiastened between said clamp bars to permit rotation of said work engagingmember rela tive to said jaw.

2. A tenter clip as in of said jaw comprises a cylindrical work engagingmember that is held between said clamp bars, said clamp bars beingmounted on said jaw tor pivotingmovernent relative to said jaw on anaxis generally perpendicular to the pivoting axis of said'jaw.

3. A tenter clip comprising a body having a fixed lower jaw member and arelative movable upper jaw member, said upper jaw member being mountedfor pivoting movement through an are greater than the distance betweenthe axis of pivoting of the upper jaw member and thelower jaw member,said lower jaw member having a hardened fiat engaging surface, the.pivoting jaw member having a cylindrical surface engage ing member, apair of clamp bars pivotally mounted on said upper jaw member on angenerally perpendicue larto the pivoting axis thereof, said cylindricalsurface engaging member being received between said clamp bars forselective rotationabout its own axis.

References Cited in the file of this patent N T S T S PA ENTS claim 1wherein said'free end

